Power semiconductor modules include insulated gate bipolar transistor (IGBT) power devices controlling the switching of a large current, and diodes interrupting a reverse current generated during the switching. The power semiconductor modules are widely used in, for instance, home appliances or motor vehicles as main components of power converters.
The power semiconductor modules have been recently used in a severe environment such as a high-temperature environment or an increase in current to be controlled. For use under such a severe environment, the power semiconductor device, such as the IGBT power device needs to have high reliability enough for a long-term normal operation under a use environment where temperature greatly varies. In addition, the power semiconductor device needs to have high heat resistance enough for its operation under high temperature resulting from an increase in heat generated from a semiconductor chip included in the power semiconductor device due to the passage of a large current.
In particular, a die-bonding agent, a joining material containing solder or metal particles, has been conventionally used so that the power semiconductor device is highly resistant to heat. For instance, one technique is disclosed in which heat generated in a semiconductor substrate is dissipated from its back surface through a lead frame (e.g., see Patent Document 1).
Further, in another technique, provided is a semiconductor device including the following: a surface electrode (Al electrode) formed on a surface of a bare chip; a laminated metal layer consisting of Ni-plated and Au-plated layers formed on the surface electrode through electroless plating; and a peripheral pressure-tight structure formed on a side surface of the surface electrode. The semiconductor device is configured such that heat is dissipated from the surface of the bare chip through the laminated metal layer (e.g., see Patent Document 2).
Still further, disclosed is a bump structure consisting of a piece of sintered metal and a piece of solder, and disposed on an electrode (e.g., see Patent Document 3).